what happens to data entered into form if user loses connectivity?

what happens to data entered into form if user loses connectivity?

Im designing an app for data entry  and was curious what happens if connection is lost (or user goes into airplane mode).
For mobile users, I'd expect that the reports will be unavailable, but will the form be unable to be accessed?
For PC use... Is there a way to have it store records locally until connectivity is restored, then automatically push them back up to the cloud once connection returns? My users travel a lot and I think being able to enter data while in flight would be valuable.